<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="./css/bootstrap.min.css">
    <title>Document</title>
    <style>
        .box{
            border: 1px solid gray;
           background-color: #ddd;
        }
        .red{
            color: white;
            background-color: red;
        }  
        .b{
            height: 200px;
            background-color: yellow;
        }
    </style>
</head>
<body>
    <script src="./js/jquery.min.js"></script>

    <div class="container">
        <div class="row box">
           <button class="btn btn-secondary">显示</button>
            <button class="btn btn-secondary">隐藏</button>
        </div>
       
    </div>

<script>
    $(function(){
       
        $('.box:first').click(function () {

            $('b').show();
            console.log('show')
            
        })
        $('.b').click(function () {
            
            $('b').hide('low','linear');
            console.log($('b').index())

        })
    })
        
</script>
</body>
</html>